Preoperative surgical simulation

ABSTRACT

An apparatus for simulating an image-guided procedure. The system comprises an input for receiving a three-dimensional (3D) medical image depicting an organ of a patient, a model generation unit for generating a 3D anatomical model of the organ according to the 3D medical image, and a simulating unit for simulating a planned image-guided procedure on the patient, according to the 3D anatomical model.

FIELD AND BACKGROUND OF THE INVENTION

The present invention relates to an apparatus and a method forperforming a simulated image-guided medical procedure and, moreparticularly, but not exclusively to performing a simulated image-guidedprocedure according to a three-dimensional (3D) model of an organ thatis based on a 3D medical image.

Medical imaging is generally recognized as important for diagnosis andpatient care with the goal of improving treatment outcomes. In recentyears, medical imaging has experienced an explosive growth due toadvances in imaging modalities such as x-rays, computed tomography (CT),magnetic resonance imaging (MRI) and ultrasound. These modalitiesprovide noninvasive methods for studying internal organs in vivo, butthe amount of data is relatively large and when presented as twodimensional (2D) images, it generally requires an anatomist/radiologyspecialist for interpretation. Unfortunately, the cost incurred inmanual interpretation of this data is prohibitive for routine dataanalysis. The 2D slices can be combined to generate a 3-D volumetricmodel.

Such medical imaging systems allow the performance of minimally invasivetherapeutic procedures. These procedures are typically carried out in aCathLab, where a physician wishes to assess the functions of internalorgan such as the heart and coronary artery or to perform proceduressuch as coronary angioplasty.

Most radiology yields recorded images such as 2D X-ray films or 3Dmedical images such as CT and MRI scans. Mild dosage interactivelycontrolled X-Ray, also known as fluoroscopy, allows a physician tomonitor actively an operation at progress. Interventional radiology isthe specialty in which the radiologist and cardiologists utilizes realtime radiological images to perform therapeutic and diagnosticprocedures. Interventional radiologists currently rely on the real-timefluoroscopic 2D images, available as analog video or digital informationviewed on video monitors.

However, these procedures involve delicate and coordinated handmovements, spatially unrelated to the view on a video monitor of theremotely controlled surgical instruments. Depth perception is lacking onthe flat video display and therefore it is not an easy task to learn tocontrol the tools through the spatially arbitrary linkage. A mistake inthis difficult environment can be dangerous. Therefore, a high level ofskill is required, and a realistic training of these specialists is acomplex task. In addition, usually there is no direct engagement of thedepth perception of the radiologist, who must make assumptions about thepatient's anatomy to deliver therapy and assess the results.

Medical simulators that can be used to train such medical specialistshave significant potential in reducing healthcare costs through improvedtraining, better pre-treatment planning, and more economic and rapiddevelopment of new medical devices. Hands-on experience becomes possiblein training, before direct patient involvement that will carry asignificant risk.

Image-guided procedures, such as vascular catheterization, angioplasty,and stent placement, are specially suited for simulation because theytypically place the physician at-a-distance from the operative sitemanipulating surgical instruments and viewing the procedures on videomonitors.

For example, U.S. Pat. No. 6,062,866 published on May 16, 2000 describesa medical model for teaching and demonstrating invasive medicalprocedures such as angioplasty. The model is a plastic, transparentthree-dimensional, anatomically correct representation of at least aportion of the vascular system and in a preferred embodiment wouldinclude the aorta, coronary artery, subclavian arteries, pulmonaryartery and renal arteries each defining a passageway or lumen. An accessport is provided so that actual medical devices, such as a guide andcatheter may be inserted to the location-simulated blockage. Fluid mayalso be introduced to simulate realistically in vivo conditions.Simulated heart chambers of similar construction may also be attached tothe aortic valve to enhance further the representation of invasiveprocedures.

More complex simulation systems that provide more accurate, linkedvisual and tactile feedback during the training is disclosed in U.S.Patent Application No. 2003/0069719 published Apr. 10, 2003 thatdescribes an interface device and method for interfacing instruments toa vascular access simulation system serve to interface peripherals inthe form of mock or actual medical instruments to the simulation systemto enable simulation of medical procedures. The interface deviceincludes a catheter unit assembly for receiving a catheter needleassembly, and a skin traction mechanism to simulate placing skin intraction or manipulating other anatomical sites for performing a medicalprocedure. The catheter needle assembly and skin traction mechanism aremanipulated by a user during a medical procedure. The catheter unitassembly includes a base, a housing, a bearing assembly and a shaft thatreceives the catheter needle assembly. The bearing assembly enablestranslation of the catheter needle assembly, and includes bearings thatenable the shaft to translate in accordance with manipulation of thecatheter needle assembly. The shaft typically includes an encoder tomeasure translational motion of a needle of the catheter needleassembly, while the interface device further includes encoders tomeasure manipulation of the catheter needle assembly in various degreesof freedom and the skin traction mechanism. The simulation systemreceives measurements from the interface device encoders and updates thesimulation and display, while providing control signals to the forcefeedback device to enable application of force feedback to the catheterneedle assembly.

Another example for a simulating system that is designed to simulate animage guiding procedure according to a predefined and fixed module isdisclosed in U.S. Pat. No. 6,538,634 published on Mar. 25, 2003.

These simulation systems and other known simulation systems are based onpredefined models, which are acquired and enhanced before the systemsbecome operational or during a maintenance thereof, such as updating thesystem. Usually, a library that comprises virtual models which arestored in a related database is connected to the simulation system.During the operational mode, the system simulates an image-guidedprocedure according to one of the virtual models that has been selectedby the system user.

Though such systems allow physicians and trainees to simulateimage-guided procedures, the simulated image-guided procedures aremodeled according to predefined or randomly changed models of an organ,a human body system, or a section thereof. As such, the physician or thetrainee is trained using a model of a virtual organ that is notidentical to the organ that he or she is about to perform an operativeimage-guided procedure on.

Moreover, when a virtual model is used, the simulation system cannot beused for accurately simulating an operation that has been performed on areal patient. Therefore, the currently used simulation systems cannot beused for going back over an operation that went wrong or for didacticpurposes.

There is thus a widely recognized need for, and it would be highlyadvantageous to have, a system for simulating image-guided procedures,devoid of the above limitations, that can simulate in a more realisticmanner the image-guided procedure that the physician is about toperform.

SUMMARY OF THE INVENTION

According to one aspect of the present invention there is provided anapparatus for simulating an image-guided procedure. The apparatuscomprises an input for receiving a three-dimensional (3D) medical imagedepicting an organ of a patient, a model generation unit configured forgenerating a 3D anatomical model of the organ according to the 3Dmedical image, and a simulating unit configured for simulating animage-guided procedure planned for the patient according to the 3Danatomical model.

Preferably, the apparatus further comprises a segmentation unitoperatively connected to the model generation unit, the segmentationunit being configured for segmenting the organ in the 3D medical imageto a plurality of areas, the segmented organ image being used forgenerating the 3D anatomical model.

Preferably, the 3D anatomical model is a model of a tract.

More preferably, the tract is a member of the following group: avascular tract, a urinary tract, a gastrointestinal tract, and a fistulatract.

Preferably, the 3D medical image is a member of the following group:computerized tomography (CT) scan images, magnetic resonance imager(MRI) scan images, ultrasound scan images, and positron emissiontomography (PET)-CT scan images.

Preferably, the planned image-guided procedure is an angioplastyprocedure.

Preferably, the apparatus further comprises a user interface operativelyconnected to the model generation unit, the user interface allows a userto instruct the model generation unit during the generation of the 3Danatomical model.

Preferably, the simulated planned image-guided procedure is used as astudy case during a learning process.

Preferably, the simulated planned image-guided procedure is used todemonstrate a respective image-guided procedure to the patient.

Preferably, the simulated planned image-guided procedure is used todocument preparation to an operation.

Preferably, the input is configured for receiving a four dimensional(4D) medical image depicting the organ during a certain period, themodel generation unit configured for generating a 4D organ model of theorgan according to the 4D medical image, the simulating unit configuredfor simulating an image-guided procedure planned for the patientaccording to the 4D organ model.

Preferably, the organ is a member of a group comprising: an anatomicalregion, a human body system, an area of an organ, a number of areas ofan organ, a section of an organ, and a section of a human body system.

According to one aspect of the present invention there is provided amethod for performing a simulated image-guided procedure. The methodcomprises the following steps: a) obtaining a three-dimensional (3D)medical image depicting an organ of a patient, b) producing a 3Danatomical model of the organ according to the 3D medical image, and c)simulating an image-guided procedure planned for the patient accordingto the 3D model.

Preferably, the method further comprises a step al) between step a) andb) of segmenting the organ in the 3D medical image to a plurality ofareas, the producing of step b) is performed according to the segmented3D medical image.

Preferably, the planned image-guided procedure is an angioplastyprocedure.

Preferably, the producing comprises a step of receiving generationinstructions from a system user, the generation instructions being usedfor defining the 3D model.

Preferably, the simulating comprises displaying the organ.

More preferably, the method further comprises a step of allowing asystem user to mark labels for the planned image-guided procedureaccording to the display.

Preferably, the planned image-guided procedure is an angioplastyprocedure.

Preferably, the simulation is a pre-operative surgical simulation.

Preferably, the 3D anatomical model is a model of a tract.

Preferably, the 3D anatomical model is a tract model.

More preferably, the tract model define a member of the following group:a vascular tract, a urinary tract, a gastrointestinal tract, and afistula tract.

Preferably, the obtaining comprises a step of obtaining a fourdimensional (4D) medical image depicting the organ during a certainperiod, the producing comprises a step of producing a 4D model of theorgan according to the 4D medical image, the simulating is performedaccording to the 4D model.

Preferably, the organ is a member of a group comprising: an anatomicalregion, a human body system, an area of an organ, a number of areas ofan organ, a section of an organ, and a section of a human body system.

Unless otherwise defined, all technical and scientific terms used hereinhave the same meaning as commonly understood by one of ordinary skill inthe art to which this invention belongs. The materials, methods, andexamples provided herein are illustrative only and not intended to belimiting.

Implementation of the method and system of the present inventioninvolves performing or completing certain selected tasks or stepsmanually, automatically, or a combination thereof. Moreover, accordingto actual instrumentation and equipment of preferred embodiments of themethod and system of the present invention, several selected steps couldbe implemented by hardware or by software on any operating system of anyfirmware or a combination thereof. For example, as hardware, selectedsteps of the invention could be implemented as a chip or a circuit. Assoftware, selected steps of the invention could be implemented as aplurality of software instructions being executed by a computer usingany suitable operating system. In any case, selected steps of the methodand system of the invention could be described as being performed by adata processor, such as a computing platform for executing a pluralityof instructions.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is herein described, by way of example only, withreference to the accompanying drawings. With specific reference now tothe drawings in detail, it is stressed that the particulars shown are byway of example and for purposes of illustrative discussion of thepreferred embodiments of the present invention only, and are presentedin order to provide what is believed to be the most useful and readilyunderstood description of the principles and conceptual aspects of theinvention. In this regard, no attempt is made to show structural detailsof the invention in more detail than is necessary for a fundamentalunderstanding of the invention, the description taken with the drawingsmaking apparent to those skilled in the art how the several forms of theinvention may be embodied in practice.

In the drawings:

FIG. 1 is a schematic representation of a pre-operative simulator forsimulating an image-guided procedure, according to one preferredembodiment of the present invention;

FIG. 2A is a graphical representation of the Hounsfield scale, whichmeasures attenuation of X-Ray radiation by a medium. Hounsfield valuesof different human tissues are marked;

FIGS. 2B and 2C respectively illustrate schematically two triangularsurface models of a femur bone, one directly generated from scan data,and a coarsened variant of the segment in FIG. 2B which is generatedaccording to one preferred embodiment of the present invention;

FIG. 3 is a schematic representation of the pre-operative simulator ofFIG. 1 with a detailed description of the simulating unit, according toone embodiment of the present invention;

FIG. 4 is an exemplary illustration of the pre-operative simulator ofFIG. 3, according to an embodiment of the present invention;

FIG. 5 is an exemplary illustration of a screen display taken during thesimulation of an image-guide procedure, according to an embodiment ofthe present invention; and

FIG. 6 is a flowchart of a method for performing a pre-operativesimulation of an image-guided procedure, according to a preferredembodiment of present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present embodiments comprise a apparatus and a method for simulatingan image-guided procedure. According to one embodiment of the presentinvention, the apparatus and the method allow a physician to set apre-operative simulation of an image-guided procedure. The pre-operativesimulation simulates an image-guided procedure that is about to beperformed on a certain patient. In order to allow such a case-specificsimulation, a 3D medical image that depicts an anatomical region of acertain patient who is about to be operated on is acquired and 3Danatomical models are generated based thereupon. Preferably, the 3Danatomical model defines the boundaries of a certain anatomy or an organsuch as a vascular tract. During the pre-operative simulation, the 3Danatomical models are used for simulating an image-guided procedure onthat region.

The principles and operation of an apparatus and method according to thepresent invention may be better understood with reference to thedrawings and accompanying description.

Before explaining at least one embodiment of the invention in detail, itis to be understood that the invention is not limited in its applicationto the details of construction and the arrangement of the components setforth in the following description or illustrated in the drawings. Theinvention is capable of other embodiments or of being practiced orcarried out in various ways. Also, it is to be understood that thephraseology and terminology employed herein is for the purpose ofdescription and should not be regarded as limiting.

A 3D medical image may be understood as a sequence of CT scan images, asequence of MRI scan images, a sequence of PET-CT scan images, a spatialimage, etc.

A medical imaging system may be understood as an MRI imaging system, aCT imaging system, a PET-CT imaging system, etc.

An organ or an anatomical region may be understood as human body organ,a human body system, an area of an organ, a number of areas of an organ,a section of an organ, a section of a human body system, etc.

Reference is now made to FIG. 1, which is a schematic representation ofa pre-operative simulator 1 for simulating an image-guided procedure,according to one preferred embodiment of the present invention. Thepre-operative simulator 1 comprises an input unit 2 for obtaining a 3Dmedical image that depicts an anatomy region of a patient and ananatomy-model generation unit 3 that is designed for generating a 3Danatomical model of an organ according to the received 3D medical image.The pre-operative simulator 1 further comprises a simulating unit 4 forsimulating an image-guided procedure according to the three-dimensionalmodel, as described below.

The input unit 2 preferably allows the system for simulatingimage-guided procedure 1 to fetch the 3D medical image from a medicalimages server such as a picture archiving communication system (PACS)before being accessed by the physicians. The PACS server comprises anumber of computers, which are dedicated for storing, retrieving,distributing and presenting the stored 3D medical images. The 3D medicalimages are stored in a number of formats. The most common format forimage storage is digital imaging and communications in medicine (DICOM).Preferably, the fetched 3D medical image is represented in a 3D array,preferably of 512·512·150 voxels.

In one embodiment, the input unit 2 receives as input a raw 3D dataarray, composed as a pre-fetched and pre-parsed DICOM image. Thesegmentation is not limited to a specific modality. Preferably, the 3Dmedical image is a CT scan. In such an embodiment, each voxel isrepresented by a single measured value, physically corresponding to thedegree of X-ray attenuation of a respective location in the depictedorgan. Preferably, the data acquisition modality is CT-angiography(CTA).

The input unit 2 may be adjusted to receive the 3D medical image from aPACS workstation, a computer network, or a portable memory device suchas a DVD, a CD, a memory card, etc.

The received 3D medical image is forwarded to the anatomy-modelgeneration unit 3 that is designed for generating the 3D anatomicalmodel, as described above. Preferably, the anatomy-model generation unit3 comprises a 3D image segmentation unit that is used for segmenting thereceived 3D medical image into anatomical structures. The segmentationis performed either automatically or semi-automatically. In oneembodiment, a standard automatic segmentation procedure is used forsegmenting the image.

Preferably, the segmentation is based on a procedure in which relevantvoxels of the received raw 3D data array are isolated. For example, ifthe raw 3D data array is based on a CT scan, the physical attenuation isscaled in HUs, where the value −1000 HU is associated with air and thevalue 0 HU is associated with water, as shown at FIG. 2A. On such ascale, different tissue types have different typical HU ranges. Thetypical attenuation of a specific tissue is used to isolate it in a 3Darray of CT data. For example, the value of voxels that depict lungs isusually between −550 HU and −450 HU and the value of voxels that depictbones is approximately between 450 HU and 1000 HU.

In such an embodiment, the HU values of voxels of the 3D medical imageare used for isolating the voxels in the tissue of interest. Preferably,in order to improve precision of the segmentation procedure, intravenouscontrast enhancement (ICE) components, such as Barium, Iodine or anyother radiopharmaceutical component, are applied when the 3D medicalimage is taken. The ICE components increase the HU value of bloodvessels to the HU value of bones and sometimes beyond. Such an incrementresults in a higher contrast between the vessel voxels and thesurrounding that can improve the segmentation procedure. Preferably, thesegmentation procedure is adapted to segment a subset of scanned voxelsfrom the 3D medical image, wherein the stored values of the voxels inthe subset is in a predefined range. In one embodiment, all the voxelswith stored values in the range of blood vessels is segmented andtagged.

In one embodiment of the present invention, a triangle mesh is computedfrom the raw 3D data array of the HU values. Preferably, a variant ofthe marching cubes algorithm is used for initial generating the trianglemesh, see Marching Cubes: A High Resolution 3D Surface ConstructionAlgorithm”, William E. Lorensen and Harvey E. Cline, Computer Graphics(Proceedings of SIGGRAPH '87), Vol. 21, No. 4, pp. 163-169. The trianglemesh is used for surface construction of segments in the 3D medicalimage. The mesh obtained by the variant of the marching cube algorithmbounds the desired volume of the segment. As the segment is obtained inthe resolution of the 3D medical image, it may be extremely fine.Therefore, preferably, an additional decimation processing stage iscarried out, in which the mesh is coarsened and the level of surfaceapproximation of the segments is reduced.

Preferably, an Edge-Collapse operation is used for the coarsening, seeHoppe, H. Progressive meshes. In Proc. SIGGRAPH '96, pages 99-108,August 1996 and Hussain, M., Okada, Y. and Niijima, K. Fast, simple,feature-preserving and memory efficient simplification of trianglemeshes. International Journal of Image and Graphics, 3(4):1-18, 2003. Anexample for such decimation is depicted in FIGS. 2B and 2C thatrespectively depict a schematic illustration a segmented femur bone anda coarsened variant of the segmented femur bone that has been generatedby applying the aforementioned decimation processing. Preferably, the 3Dmedical image is represented in a 3D array of 512×512×150, wherein eachvoxel is preferably represented by a value in one of the followingformats: 8-bit (1 byte storage), 12-bit (2 byte storage), 16 bit (2 bytestorage), and a single-precision floating point (4 byte storage).

Preferably, the segmentation procedure is adapted to segment the anatomythat is depicted in the received 3D medical image. Different anatomicparts have different characteristics that affect segmentation.

During the image-guided procedures, a catheter or the like is conveyedby a physician via a certain tract. Therefore, the segmentationprocedure's object is to identify such a tract and to segment it or tosegment all the areas that delimit that tract.

For example, if the received 3D medical image depicts a cervical portionof the human spine and the image-guided procedure is an angioplastyprocedure, such as carotid stenting, the carotid artery is the tractthrough which the catheter or alike is conveyed. In such a case, thecarotid artery should be segmented. The artery net possesses a-prioriknown traits that can be exploited to enhance and verify the fidelity ofthe segmentation stage. For example, if the area is a cervical portionand the procedure is carotid stenting, the following anatomicalstructures are exploited: the thoracic aorta, the brachiocephalic trunk,the Subclavian arteries, the carotid arteries, and the vertebralarteries.

Preferably, blood vessels in the image of the organ are identified andsegmented during the segmentation procedure. Preferably, during thesegmentation the centerline, the radius and the inter-connectivity ofeach one of the main blood vessels in the image are identified andregistered.

Preferably, the anatomy-model generation unit 3 is connected to a userinterface (not shown). In such an embodiment, a simulator user may beasked, for example, to mark one or more points on a depicted tract. Forexample, if the received 3D medical image depicts a cervical portion ofthe human spine and the image-guided procedure is an angioplastyprocedure, the simulator user may be required to mark the left carotidartery as a starting point for the automatic segmentation.

When the segmentation process is completed, a segmented version of the3D image or an array that represents the segmented areas and the tractsis generated. The segmented areas can be represented in several formatsand sets of data. Preferably, the segmented 3D image is represented byusing one or more of the following sets of data:

-   a. A cubic Catmull-Rom 3D spline description of a central curve of    each artery or any other tract portion;-   b. A tree description, graph description or any other description    that describes the connectivity between arteries or any other tract    portions. For example, such a description describes in which point    an artery X emanates an artery Y;-   c. A cubic Catmull-Rom 2D spline description of the radius of each    artery at each point on its central curve;-   d. A triangular surface mesh that describes the surface of the    vasculature anatomy;-   e. Polygonal meshes describing other organs captured in the    scan—Lungs, heart, kidneys, etc; and-   f. Classification of each raw data voxel to its designated part of    anatomy (a vessel voxel, a kidney voxel, etc.).

The segmented 3D medical image or an array representing segments in the3D medical image is forwarded to the simulating unit 4.

It should be noted that the pre-operative simulator 1 may also be usedto simulate an image-guided procedure according to a four dimensional(4D) image, which is a set of 3D medical image that depicts a certainorgan during a certain period. In such an embodiment, a 4D image isreceived by the input 2. The received 4D medical image is forwarded tothe anatomy-model generation unit 3 that is designed for generating the4D model. Preferably, the anatomy-model generation unit 3 comprises a 4Dimage segmentation unit that is used for segmenting the received 4Dmedical image into anatomical structures. The segmentation is performedeither automatically or semi-automatically. In one embodiment, each oneof the 3D medical image that comprise the received 4D medical image isseparately segmented, as described below.

Reference is now made to FIG. 3, which is a block diagram representingthe pre-operative simulator 1, which is depicted in FIG. 1, thecomponents of the simulating unit 4, and a planning module 51, accordingto one embodiment of the present invention.

The simulating unit 4 preferably comprises two subsystems. The firstsubsystem is an intervention simulator device 50 constituted by a dummyinterventional instrument 52, motion detectors 53, a movementcalculation unit 57, an image display device 58, and a force feedbackmechanism 54. The second subsystem is a simulation module 55 that hasthe functions of receiving inputs from the motion detectors 53,analyzing the inputs using the movement calculation unit 57, translatingthe outcome to visual and tactile outputs and transferring them to thedisplay device 58 and to the force feedback mechanism 54. The simulationmodule 55 has also the functions of receiving the segmented 3D medicalimage from the anatomy-model generation unit 3, wherein the receivedsegmented 3D medical image is already translated to a 3D model thatsimulates the organ that is depicted in the segmented 3D medical image.As described above the segmented 3D medical image is based on a 3Dmedical image that is received from the actual patient who is about tobe operated on.

Reference in now made to FIG. 4, which is an exemplary illustration ofthe aforementioned pre-operative simulator 1 for simulation of animage-guided procedure according to an embodiment of the presentinvention. The dummy intervention instrument 52 and the image displaydevice are as in FIG. 3, however FIG. 4 further depicts an enclosure 62,a computer processor 64, and a user input interface 65. In use, aphysician prepares himself for the operative image-guided procedure bymanipulating the dummy interventional instrument 52 that is preferably adummy catheter. The dummy interventional instrument 52 is inserted intoa cavity 66 within an enclosure 62 that comprises the motion detectorsand force feedback components (not shown), such as resisting forcegenerators, of the force feedback mechanism (not shown). As thephysician manipulates the dummy interventional instrument 52, tactileand visual feedbacks are determined according to the position of dummyinterventional instrument 52 within the enclosure 62 in respect to theaforementioned 3D model of the simulated organ. Visual feedback isprovided in the form of a display on the image display device 58 andtactile feedback is provided from the force feedback components withinthe enclosure 62. The visual and tactile feedbacks, which arerespectively displayed on the image display device 58 and imparted onthe dummy interventional instrument 52 are designed to improve technicaland operational skills of the physician. The visual feedback is given bya display device 58 that displays a sequence of consecutive images,which are based on a 3D model that is based on the received 3D medicalimage. The tactile feedback is given by imparting different pressures onthe dummy interventional instrument respective to the movement signalsas received from the imaging simulation module, in respect to the 3Dmodel that is based on the received 3D medical image. The differentpressures simulate the actual tactile feeling the physician experiencesduring a real image-guided procedure and reflects the actual reaction ofthe patient tissues to the dummy interventional instrument 52manipulation.

The image display device 58 displays a real time feedback image astransferred from the simulation module (not shown). The real timefeedback image represents a visual image as seen if an interventionalinstrument was inserted into the organ of the patient which is about tobe operated on. The visual image is an accurate and realistic simulationof the visual data that would be received from the related organ.

Preferably, the simulation module and the anatomy-model generation unit3 are supported by a processor such as an Intel Pentium Core-Duo, withan nVidia GeForce-6+ (6600 onwards) GPU.

Reference is now made, once again, to FIG. 3. The simulation module 55,through the processor, is utilized to prepare simulated organ visualimages as displayed on the screen during the operative image-guidedprocedure. The visual feedback is rendered for simulating a visualdisplay of the organ during the simulated image-guided procedure, asshown in FIG. 5 that is a simulated fluoroscopic image of Carotidstenting. Preferably, the simulation module 55 simulates a number ofvascular tracts, according to the received 3D medical image. At the sametime, the simulation module 55 receives navigation signals from themotion detectors 53, which are located along the enclosure cavity. Thesimulation module 55 uses the processor to calculate the position of thedummy interventional instrument 52 within the enclosure cavity accordingto the navigation signals and updates the visual image of the organ, asdescribed above, with the instantaneous respective position of the dummyinterventional instrument 52. Moreover, the simulation module 55simulates realistic interaction between the simulated instrument, suchas a catheter, and the simulated anatomy, including—but not limitedto—catheter twist and bend, vessel flexing and optionally vesselrupture.

In addition, and in correspondence with the visual information, thesimulation module 55 also instructs the components of the force feedback54 to impart pressure on the dummy interventional instrument 52 in amanner that simulates the instantaneous tactile feedback of theprocedure. Such visual images and tactile feedback simulate the actualfeedback as received during an actual medical procedure as performed onan actual subject and therefore reflect to the physician the currentlocation and bending of the interventional instrument along thesimulated organ. Clearly, the pre-operative simulator 1 is not bound tothe simulation of a particular organ, such as a vascular tract, but canreflect a visual display of various elements and organs relative to theinstantaneous position of the interventional instrument. Simulators ofimage-guided procedures are not described here in greater detail as theyare generally well known and already comprehensibly described in theincorporated patents and in publications known to the skilled in theart.

The pre-operative simulator 1 is designed to allow a physician toconduct a pre-operative surgical simulation of the image-guidedprocedure he or she is about to perform on a certain patient. In such anembodiment, the physician refers the certain patient to a medicalimaging system for acquiring a 3D medical image of an organ that isabout to be operated on. The acquired 3D medical image is then forwardedto the PACS server. Later on, the acquired 3D medical image is obtainedby the pre-operative simulator 1 from the PACS server. The 3D medicalimage is used as the basis for a 3D anatomical model of the organ. The3D anatomical model is generated by a segmentation unit that is designedfor segmenting the organ into a number of areas, as described in greaterdetail above.

It should be noted that such a pre-operative simulator 1 can also beused for explaining and demonstrating to the patient the details of hispathology and the operation he is about to undergo.

In one embodiment of the present invention, the pre-operative simulator1 can also be used as a learning tool. Known simulators are designed tosimulate an image-guided procedure on a predefined model of a virtualorgan. As the simulated organ is a virtual organ, the trainer cannot beexperienced in diagnosing a real patient in a manner that allows him toreceive a more comprehensive overview of the related case. As opposed tothat, the pre-operative simulator 1 allows the performance ofpatient-specific simulations of real anatomy, as described above. Assuch, the pre-operative simulator 1 can be used for teaching a very realcase, with real anatomy, lesions, problems, conflicts and resolutions.Physicians can experience a more realistic image-guided procedure, anddecisions may be taken during the simulated image-guided procedure basedon the overall medical history and the medical condition of the patienthimself.

In one embodiment of the present invention, the pre-operative simulator1 can also be used as a planning tool. The planning module 51, which isdepicted in FIG. 3, is preferably connected to the image display device58 or to any other display device and to a user interface. The planningmodule 51 supports tools for allowing physicians to plan an operativeimage-guided procedure according to the aforementioned case-specificsimulation. The module preferably allows the physician to sketch and totake notes during the image-guided procedure simulation. Preferably, theimage display device 58 is a touch screen that allows the physician tosketch a track that depicts the maneuvers that he intends to take duringthe operative image-guided medical procedure. Moreover, in such anembodiment, the physician can mark problematic areas of the depictedorgan. In one preferred embodiment, the image-guided proceduresimulation is an angioplasty procedure simulation. The physician can usethe touch screen to sketch the boundaries of the tract through which heintends to perform the procedure or a portion thereof.

In one embodiment of the present invention, the pre-operative simulator1 can also be used as an analyzer tool for going back over performedoperations. As described above, the model of the operated organ isgenerated according to a medical image of an organ which is about to beoperated. In one embodiment of the present invention the pre-operativesimulator 1 is used for performing a reenactment of the image-guidedprocedure that has been performed on the patient. Such a reenactment isperformed as an image-guided procedure simulation, as described above.As the model that is used by the pre-operative simulator 1 simulates theoperated on organ, the reenactment is realistic and allows thephysicians to be prepared better to the operation.

Reference is now made to FIG. 6, which is a flowchart of a method forperforming a simulated image-guided procedure, according to oneembodiment of present invention.

The method depicted in FIG. 6 allows a physician to conduct a clinicalpre-operative simulation of the image guided procedure he or she isabout to perform. Such a simulation allows the physician to take safeand unrushed clinical decisions based on a 3D medical image of thepatient that is about to be operated on.

During the first step, as shown at 201, a 3D medical image depicting anorgan of a patient is obtained. The 3D medical image has been takenusing a medical imaging system and obtained, for example via a PACSserver or a portable memory device, as described above. The 3D medicalimage depicts an organ of a patient that is about to be operated on.During the following step, as shown at 202, a 3D model of the anatomy isproduced according to the received 3D medical image. The 3D modeldefines the boundaries of areas in the anatomy such as a certain tract.In the following step, as shown at 203, a simulation of an image-guidedprocedure on the patient is held according to the 3D model that has beenconstructed in the previous step. The simulation of the image-guidedprocedure allows a physician to prepare himself to the operativeimage-guided procedure. Based on the simulation, the physician canchoose the fittest angles and the tools. Furthermore, the user can markpitfalls, such as hard-to navigate zones or misleading view angles inadvance.

For example, if the simulated image-guided procedure is an angioplastyprocedure, the physician can choose, in advance, the size and the typeof the catheter, the balloon, and the stent he is going to use duringthe operation. Moreover, gaining acquaintance with the specific anatomyof the patient in advance may result in reducing contrast injection andX-ray exposure. In angioplasty procedure, for example, the duration ofthe X-ray exposure periods depends on the time it takes the physician tomaneuver the catheter in the relevant anatomy region. If the physicianalready simulated the angioplasty procedure using the aforementionedsystem, he is already familiar with the specific region and thereforecan easily maneuver the catheter during the actual angioplastyprocedure.

It is expected that during the life of this patent many relevant devicesand systems will be developed and the scope of the terms herein,particularly of the terms a 3D model, an imaging device, a simulatingunit, motion detectors, a 3D medical image, and an image-guidedprocedure are intended to include all such new technologies a priori.

It is appreciated that certain features of the invention, which are, forclarity, described in the context of separate embodiments, may also beprovided in combination in a single embodiment. Conversely, variousfeatures of the invention, which are, for brevity, described in thecontext of a single embodiment, may also be provided separately or inany suitable subcombination.

Although the invention has been described in conjunction with specificembodiments thereof, it is evident that many alternatives, modificationsand variations will be apparent to those skilled in the art.Accordingly, it is intended to embrace all such alternatives,modifications and variations that fall within the spirit and broad scopeof the appended claims. All publications, patents, and patentapplications mentioned in this specification are herein incorporated intheir entirety by reference into the specification, to the same extentas if each individual publication, patent or patent application wasspecifically and individually indicated to be incorporated herein byreference. In addition, citation or identification of any reference inthis application shall not be construed as an admission that suchreference is available as prior art to the present invention.

1. An apparatus for simulating an image-guided procedure, comprising: aninput unit to receive a three-dimensional (3D) medical image specific toan actual patient undergoing a specific medical procedure obtained by amedical imaging system depicting an anatomical region of the patientundergoing the specific medical procedure wherein the medical image isobtained after administering an intravenous contrast enhancement (ICE)component to the patient in order to improve precision of an automatic3D segmentation process related to a soft tissue; a 3D segmentation unitto perform the automatic segmentation process on the 3D medical imagespecific to the patient and for producing a segmented 3D medical image,wherein the automatic segmentation process comprises classification ofdata voxels according to respective anatomical parts of said anatomicalregion and registration of said anatomical region; a model generationunit to generate a 3D anatomical model of said anatomical region,according to said segmented 3D medical image; and a simulating unit tosimulate an image-guided procedure planned for said patient according tosaid 3D anatomical model.
 2. The apparatus of claim 1, wherein the 3Dmedical image is represented in a 3D data array and the 3D segmentationunit receives as input the 3D data array.
 3. The apparatus of claim 1,where said 3D medical image is represented in digital imaging andcommunication in medicine (DICOM) format and said 3D anatomical model ispresented by sets of data comprising a 3D spline description andpolygonal meshes representation.
 4. The apparatus of claim 1, whereinsaid 3D anatomical model is a model of a tract and said tract is amember of the following group: a vascular tract, a urinary tract, agastrointestinal tract, and a fistula tract.
 5. The apparatus of claim1, wherein said 3D medical image is a member of the following group:computerized tomography (CT) scan images, magnetic resonance imager(MRI) scan images, ultrasound scan images, and positron emissiontomography (PET)-CT scan images.
 6. The apparatus of claim 1, whereinsaid planned image-guided procedure is an angioplasty procedure.
 7. Theapparatus of claim 1, further comprising a user interface operativelyconnected to said model generation unit, said user interface is toaccept input data that identifies a location in the 3D medical image; 8.The apparatus of claim 1, wherein said simulated planned image-guidedprocedure is used as a study case during a learning process.
 9. Theapparatus of claim 1, wherein said simulated planned image-guidedprocedure is used to demonstrate a respective image-guided procedure tosaid patient.
 10. The apparatus of claim 1, wherein said simulatedplanned image-guided procedure is used to document preparation to anoperation.
 11. The apparatus of claim 1, wherein said input unit isconfigured for receiving a four dimensional (4D) medical image, which isa set of consecutive 3D medical images that depicts said anatomicalregion during a time period, said model generation unit is configuredfor generating a 4D anatomical model according to said 4D medical image,said simulating unit is configured for simulating an image-guidedprocedure planned for said patient according to said 4D anatomicalmodel.
 12. The apparatus of claim 1, wherein said anatomical region is amember of a group comprising: an organ, a human body system, an area ofan organ, a number of areas of an organ, a section of an organ, and asection of a human body system.
 13. A method for performing a simulatedimage-guided procedure, said method comprising: obtaining, by a medicalimaging system, a three-dimensional (3D) medical image specific to anactual patient undergoing a specific medical procedure, depicting ananatomical region of the patient undergoing the specific medicalprocedure, wherein the medical image is obtained after administering anintravenous contrast enhancement (ICE) component to the patient in orderto improve precision of an automatic 3D segmentation process related toa soft tissue; performing, by a computer processor, the automatic 3Dsegmentation process on the 3D medical image specific to the patient toproduce a segmented 3D medical image, wherein the automatic segmentationprocess comprises classifying data voxels according to respectiveanatomical parts of said anatomical region and registering saidanatomical region; producing, by the computer processor, a 3D anatomicalmodel of said anatomical region according to said segmented 3D medicalimage; and simulating an image-guided procedure planned for said patientaccording to said 3D anatomical model.
 14. The method of claim 13,wherein the 3D medical image is represented in a 3D data array and the3D segmentation unit receives as input the 3D data array.
 15. The methodof claim 13, wherein said planned image-guided procedure is anangioplasty procedure.
 16. The method of claim 13 comprising: receivinginput data that identifies a location in the 3D medical image inrelation to the automatic segmentation process.
 17. The method of claim13, wherein said simulating comprises displaying said 3D anatomicalmodel as a display on an image display device coupled to the computerprocessor.
 18. The method of claim 17, further comprising a step ofallowing a system user to mark labels for said planned image-guidedprocedure according to said display.
 19. The method of claim 13, whereinsaid planned image-guided procedure is an angioplasty procedure.
 20. Themethod of claim 13, wherein said step of simulating is performed as apre-operative surgical simulation. 21-25. (canceled)